Sharing encryption keys the quantum way is exciting because it promises to be an incredibly secure way of doing encryption. In quantum cryptography, the encryption key is read by measuring the polarization of the photons being sent between computers. And according to Heisenberg’s uncertainty principle, anyone listening in on the communications would have to start messing with that polarization. And that would be detectable.

Up until now, the photons used to exchange quantum keys have been built using external lasers. But this new laser-free technique would be cheaper to mass-produce, says Sven Höfling, a group leader with the applied physics department at Würzburg University. “We can make Quantum key distribution with electrically driven sources,” he says. This is really compatible with standard semiconductor technology, meaning it could be, in principle, very cheap.”

Using about $20,000 in lab equipment, they’ve tested their link, tested over a 40 cm connection in the laboratory, he says.

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